Shader "Study/Chapter6/GrabTexture"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "Queue"="Transparent" "RenderType"="Opaque" }

        GrabPass { "_GrabTex" }

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
                float4 scrPos : TEXCOORD1;
            };

            sampler2D _GrabTex;
            float4 _GrabTex_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                //o.scrPos = ComputeGrabScreenPos(o.vertex);
                o.uv = v.uv;  //TRANSFORM_TEX(v.uv, _GrabTex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col = tex2D(_GrabTex, i.uv);
                //return i.uv.y;
                return col;
            }
            ENDCG
        }
    }
}
